Enzymatic degradation of some nanocomposites of poly(vinyl alcohol) with starch

Biodegradation profile and soil microbiota interactions of poly(vinyl alcohol)/starch-based fertilizers

Enhanced efficiency fertilizers (EEFs) are critical for sustainable agriculture, providing essential nutrients while minimizing environmental impact. However, developing EEFs that effectively degrade after use remains a significant challenge. This study investigates the biodegradation and nutrient release profiles of EEFs composed of poly(vinyl alcohol) (PVA) and starch-nutrient microspheres. EEFs were developed using a dual-layered approach: spray drying to create starch-nutrient microspheres, followed by melt processing with PVA to form pastilles. A 100-day soil biodegradation test monitored CO2 release as an indicator of microbial activity and material degradation. Comprehensive analyses, including chemical (FTIR), thermal (DSC), and morphological (SEM) assessments, were conducted. The increased CO band intensity (~1640 cm-1) after biodegradation indicated early stages of PVA degradation, accompanied by a rise in the glass transition temperature (Tg). Thermal analysis revealed nutrient release, as evidenced by a decrease in KNO3 peaks. Starch-based EEFs enhanced CO2 release and mycelial coverage, suggesting that starch-containing materials facilitated PVA degradation by improving microbial adhesion. This study underscores the potential of biodegradable EEFs to enhance soil health and reduce pollution, thereby contributing significantly to sustainable agriculture.

The strategic applications of natural polymer nanocomposites in food packaging and agriculture: Chances, challenges, and consumers' perception

Natural polymer-based nanocomposites have received significant attention in both scientific and industrial research in recent years. They can help to eliminate the consequences of application of petroleum-derived polymeric materials and related environmental concerns. Such nanocomposites consist of natural biopolymers (e.g., chitosan, starch, cellulose, alginate and many more) derived from plants, microbes and animals that are abundantly available in nature, biodegradable and thus eco-friendly, and can be used for developing nanocomposites for agriculture and food industry applications. Biopolymer-based nanocomposites can act as slow-release nanocarriers for delivering agrochemicals (fertilizers/nutrients) or pesticides to crop plants to increase yields. Similarly, biopolymer-based nanofilms or hydrogels may be used as direct product coating to extend product shelf life or improve seed germination or protection from pathogens and pests. Biopolymers have huge potential in food-packaging. However, their packaging properties, such as mechanical strength or gas, water or microbial barriers can be remarkably improved when combined with nanofillers such as nanoparticles. This article provides an overview of the strategic applications of natural polymer nanocomposites in food and agriculture as nanocarriers of active compounds, polymer-based hydrogels, nanocoatings and nanofilms. However, the risk, challenges, chances, and consumers' perceptions of nanotechnology applications in agriculture and food production and packaging have been also discussed.

Increase of resistant starch content by hydrolysis of potato amylopectin and its microstructural studies by 2D and 3D imaging

The effect of amylopullulanase treatment on recrystallization behaviour and the formation of resistant starch crystals have been investigated. Extracted potato starch (Solanum tuberosum) has been subjected to the enzymatic assisted bioprocessing without any physical or chemical treatment, where 120 min of incubation, 7 % (v/v) of enzyme and 8 mL/g of water content were found to be optimum to increase the resistant starch content by 41.88 %. The resistant starch crystals showed the characteristic behaviour of B-type allomorph with an increase in 21.32 % crystallinity. The modified crystals portrayed less reduction in actual weight when assessed by thermo-gravimetric analysis. The compact linear arrangement of the linear amylose chains within the crystallized granule of starch has been evidenced by Bright Field Microscopy. The microstructure of the resistant starch crystals showed 33.18 % reduction in porosity when the 3-dimensional structural form was analysed by X-ray micro-Computed Tomography.

Embedded Target Filler and Natural Fibres as Interface Agents in Controlling the Stretchability of New Starch and PVOH-Based Materials for Rethinked Sustainable Packaging

A structuring solution converting starch into a multiphase polymeric material was obtained through a melt compounding sequence, which can be irreversibly shaped by thermoforming into rethinked, sustainable packaging, based on the physical modification of starch with polyvinyl alcohol (PVOH), target fillers, (CaCO3 and wood flour), and a good plasticizer compatible with the polar components. Polymeric material can be thermoformed if it can be stretched without breaking in the positive temperature range, have functional properties required by the application, and keep its shape and properties after stretching for more than six months. The properties of the selected quaternary starch-based compound, fulfil the requirements for a thermoformable polymeric material due to the chemical compatibility between the components and the compounding in a selected procedure and optimal conditions wich ensure a comfortable miscibility . Most likely, the obtained miscibility can be explained only by the arrangement of the wood flour at the interface, where it acts as compatibilizer with a main role in structuring the new starch-based materials. The compatibilizer role of the wood flour was proved for the quaternary selected blend by the changing of the thermal degradation mechanism, from one with two stages for binary and tertiary blends, to one consisting of a single stage: decreasing till elimination of morphological defects, the reproducibility of the mechanical properties, stretching without breaking, and dimensional stability after stretching. Future studies will aim to achieve revised packaging for applications that require higher strength properties.

Environmental Degradation of Plastic Composites with Natural Fillers-A Review

Polymer composites are widely used modern-day materials, specially designed to combine good mechanical properties and low density, resulting in a high tensile strength-to-weight ratio. However, materials for outdoor use suffer from the negative effects of environmental factors, loosing properties in various degrees. In particular, natural fillers (particulates or fibers) or components induce biodegradability in the otherwise bio inert matrix of usual commodity plastics. Here we present some aspects found in recent literature related to the effect of aggressive factors such as temperature, mechanical forces, solar radiation, humidity, and biological attack on the properties of plastic composites containing natural fillers.

Seawater-Degradable Polymers-Fighting the Marine Plastic Pollution

Polymers shape human life but they also have been identified as pollutants in the oceans due to their long lifetime and low degradability. Recently, various researchers have studied the impact of (micro)plastics on marine life, biodiversity, and potential toxicity. Even if the consequences are still heavily discussed, prevention of unnecessary waste is desired. Especially, newly designed polymers that degrade in seawater are discussed as potential alternatives to commodity polymers in certain applications. Biodegradable polymers that degrade in vivo (used for biomedical applications) or during composting often exhibit too slow degradation rates in seawater. To date, no comprehensive summary for the degradation performance of polymers in seawater has been reported, nor are the studies for seawater-degradation following uniform standards. This review summarizes concepts, mechanisms, and other factors affecting the degradation process in seawater of several biodegradable polymers or polymer blends. As most of such materials cannot degrade or degrade too slowly, strategies and innovative routes for the preparation of seawater-degradable polymers with rapid degradation in natural environments are reviewed. It is believed that this selection will help to further understand and drive the development of seawater-degradable polymers.

Bio- and Fossil-Based Polymeric Blends and Nanocomposites for Packaging: Structure⁻Property Relationship

In the present review, the possibilities for blending of commodities and bio-based and/or biodegradable polymers for packaging purposes has been considered, limiting the analysis to this class of materials without considering blends where both components have a bio-based composition or origin. The production of blends with synthetic polymeric materials is among the strategies to modulate the main characteristics of biodegradable polymeric materials, altering disintegrability rates and decreasing the final cost of different products. Special emphasis has been given to blends functional behavior in the frame of packaging application (compostability, gas/water/light barrier properties, migration, antioxidant performance). In addition, to better analyze the presence of nanosized ingredients on the overall behavior of a nanocomposite system composed of synthetic polymers, combined with biodegradable and/or bio-based plastics, the nature and effect of the inclusion of bio-based nanofillers has been investigated.

Water-soluble polymeric xenobiotics - Polyvinyl alcohol and polyvinylpyrrolidon - And potential solutions to environmental issues: A brief review

This paper describes a potential environmental problem closely linked with the global production of water-soluble polymers such as polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP). Both polymers make up the components of a multitude of products commonly utilized by industries and households. Hence, such a widespread use of PVA and PVP in the industrial sector and among consumers (the concentration of PVP in urban wastewater is approximately 7 mg/L) could pose a considerable problem, particularly to the environment. To this end, many publications have recently highlighted the poor biodegradability of PVA, in principle influenced by numerous biotic and abiotic factors. Facts published on the environmental fate of PVP have been scant, basically reporting that it is a biologically resistant polymer. As a result, the commercially produced water-soluble polymers of PVA and PVP are essentially non-biodegradable and possess the capacity to accumulate in virtually all environmental media. Consequently, there is a chance of heightened risk to the very environmental constituents in which PVA and PVP accumulate, depending on the routes of entry and transformation processes underway in such constituents of the ecosystem. This assumption is confirmed by the findings of initial research, which is worrying. Herein, PVA was detected in a soil environment, while a relatively high concentration of PVP was found in river water. A review of the literature was conducted to summarize the current state of knowledge concerning the fate of PVA and PVP in various environments, thereby also discerning potential solutions to tackle such dangers. This paper proposes methods to enhance the biodegradability of materials containing such materials; for PVA this means utilizing a suitable polysaccharide, whereas for PVP this pertains to actuating applications that induce substances to degrade. Accordingly, while it is understandable that this work cannot fully address all the issues associated with polymeric xenobiotics, it can still serve as a guide to discerning an economically viable solution, and provide a foundation for further research.

Biodegradation and ecotoxicological impact of cellulose nanocomposites in municipal solid waste composting

Biodegradable nanocomposites were prepared from polyvinyl alcohol (PVA) and cellulose nanofiber (CNF) by using liquid nitrogen, freeze drying and hot press techniques. The effect of CNF content on the biodegradability of the films was investigated by visual observation, scanning electron microscopy (SEM), weight loss, CO₂ evolution, differential scanning calorimetry, measuring the amount of mineralized carbon of the specimens buried in municipal solid waste. Ecotoxicity was evaluated by plants growth tests with cress and spinach. The results confirmed that the weight loss of nanocomposites was lower than that of neat PVA because of the zigzag pathways of microorganisms in the CNF presence. The SEM analysis showed extensive surface roughness and cracks for all samples, indicating the initiation of biodegradation. The CO₂ evolution decreased with increasing CNF content from 0% to 10% and then, increased with further increase in the filler content (up to 30 wt%). The crystallinity of the PVA and its nanocomposites increased as a function of time because of the amorphous parts degradation. Preliminary results of the ecotoxicological test revealed that all the nanocomposites and neat PVA did not generate any negative effects on germination or development of the studied vegetal species.

Environmental performance of bio-based and biodegradable plastics: the road ahead

This review provides a critical discussion as to the future direction of plastic materials, including balancing factors such as biodegradability and longevity, effects of additive compounds, feedstock developments, and environmental considerations.

Properties and Applications of Polyvinyl Alcohol, Halloysite Nanotubes and Their Nanocomposites

The aim of this review was to analyze/investigate the synthesis, properties, and applications of polyvinyl alcohol-halloysite nanotubes (PVA-HNT), and their nanocomposites. Different polymers with versatile properties are attractive because of their introduction and potential uses in many fields. Synthetic polymers, such as PVA, natural polymers like alginate, starch, chitosan, or any material with these components have prominent status as important and degradable materials with biocompatibility properties. These materials have been developed in the 1980s and are remarkable because of their recyclability and consideration of the natural continuation of their physical and chemical properties. The fabrication of PVA-HNT nanocomposites can be a potential way to address some of PVA's limitations. Such nanocomposites have excellent mechanical properties and thermal stability. PVA-HNT nanocomposites have been reported earlier, but without proper HNT individualization and PVA modifications. The properties of PVA-HNT for medicinal and biomedical use are attracting an increasing amount of attention for medical applications, such as wound dressings, drug delivery, targeted-tissue transportation systems, and soft biomaterial implants. The demand for alternative polymeric medical devices has also increased substantially around the world. This paper reviews individualized HNT addition along with crosslinking of PVA for various biomedical applications that have been previously reported in literature, thereby showing the attainability, modification of characteristics, and goals underlying the blending process with PVA.

Sonocatalytic degradation of 2-hydroxyethyl cellulose in the presence of some nanoparticles

The degradation of 2-hydroxyethyl cellulose (HEC) by means of ultrasound irradiation and its combination with heterogeneous catalysts such as TiO2 (Rutile and Anatase), Montmorillonite Clay (MMT), ZnO and Fe3O4 nanoparticles was investigated. The effect of the type and quantity of nanoparticles, the initial molecular weight of polymer and the different ultrasonic power have been studied. Degradation behavior of HEC was studied through FTIR, XRD and SEM techniques and kinetics of degradation was studied by viscometry. Also, reduce in molecular weight (Mw) of polymer was investigated by gel permeation chromatography (GPC) analysis. The results of experiments suggested that the sonocatalytic degradation of HEC were remarkably higher than sonolytic degradation. However, the catalytic activity of nanoparticles in contrast to the ultrasonic irradiation was different. The experimental results revealed that the best HEC degradation can be obtained when the added Fe3O4 amount was 0.4 g/L. Furthermore, kinetic analysis of the polymer degradation process was carried out in this study.

Biodegradation behaviors and water adsorption of poly(vinyl alcohol)/starch/carboxymethyl cellulose/clay nanocomposites

The focus of this work is to study the effect of sodium montmorillonite (MMT-Na) clay content on the rate and extent of enzymatic hydrolysis polyvinyl alcohol (PVA)/starch (S)/carboxymethyl cellulose (CMC) blends using enzyme cellulase. The rate of glucose production from each nanocomposite substrates was most rapid for the substrate without MMT-Na and decreased with the addition of MMT-Na for PVA/S/CMC blend (51.5 μg/ml h), PVA/S/CMC/1% MMT (45.4 μg/ml h), PVA/S/CMC/3% MMT (42.8 μg/ml h), and PVA/S/CMC/5% MMT (39.2 μg/ml h). The results of this study have revealed that films with MMT-Na content at 5 wt.% exhibited a significantly reduced rate and extent of hydrolysis. Enzymatic degradation behavior of MMT-Na containing nanocomposites of PVA/S/CMC was based on the determinations of weight loss and the reducing sugars. The degraded residues have been characterized by various analytical techniques, such as Fourier transform infrared spectroscopy, scanning electronic microscopy, and UV-vis spectroscopy.

Biodegradable nanocomposite hydrogel structures with enhanced mechanical properties prepared by photo-crosslinking solutions of poly(trimethylene carbonate)-poly(ethylene glycol)-poly(trimethylene carbonate) macromonomers and nanoclay particles

Soft hydrogels with elasticity modulus values lower than 100kPa that are tough and biodegradable are of great interest in medicine and in tissue engineering applications. We have developed a series of soft hydrogel structures from different methacrylate-functionalized triblock copolymers of poly(ethylene glycol) (PEG) with poly(trimethylene carbonate) (PTMC) by photo-crosslinking aqueous solutions of the macromonomers in 2.5 and 5wt.% colloidal dispersions of clay nanoparticles (Laponite XLG). The length of the PTMC blocks of the macromonomers and the clay content determined the physicomechanical properties of the obtained hydrogels. While an increase in the PTMC block length in the macromonomers from 0.2 to 5kg/mol resulted in a decrease in the gel content, the addition of 5wt.% Laponite nanoclay to the crosslinking solution lead to very high gel contents of the hydrogels of more than 95%. The effect of PTMC block length on the mechanical properties of the hydrogels was not as pronounced, and soft gels with a compressive modulus of less than 15kPa and toughness values of 25kJm(-3) were obtained. However, the addition of 5wt.% Laponite nanoclay to the formulations considerably increased the compressive modulus and resilience of the hydrogels; swollen nanocomposite networks with compressive modulus and toughness values of up to 67kPa and 200kJm(-3), respectively, could then be obtained. The prepared hydrogels were shown to be enzymatically degradable by cholesterol esterase and by the action of macrophages. With an increase in PTMC block length in the hydrogels, the rates of mass loss increased, while the incorporated Laponite nanoclay suppressed degradation. Nanocomposite hydrogel structures with a designed gyroid pore network architecture were prepared by stereolithography. Furthermore, in the swollen state the porous gyroid structures were mechanically stable and the pore network remained fully open and interconnected.

Structure and physical properties of starch/poly vinyl alcohol/sodium montmorillonite nanocomposite films

Nanocomposites of starch, poly vinyl alcohol (PVOH), and sodium montmorillonite (Na(+)MMT) were produced by solution mixing and cast into films. Tensile strength (TS) and elongation at the break (E%) of the films ranged from 11.60 to 22.35 MPa and 28.93-211.40%, respectively, while water vapor permeability (WVP) ranged from 0.718 to 1.430 g·mm/kPa·h·m(2). In general, an increase in Na(+)MMT content (0-20%) enhanced TS and decreased E% and WVP. Use of higher molecular weight PVOH increased both TS and E% and also decreased WVP. Mechanical properties were negatively affected, but water vapor barrier properties improved with increasing starch content (0-80%). X-ray diffraction and transmission electron microscopy were used to analyze the nanostructure, and molecular conformations and interactions in the multicomponent nanocomposites were inferred from glass transition behavior. Interactions between starch and PVOH were strongest, followed by polymer/clay interactions. On the basis of this insight, a conceptual model was presented to explain the phenomena of intercalation and exfoliation in the starch/PVOH/Na(+)MMT nanocomposites.